Human polymorphonuclear leukocyte elastase is the enzyme primarily responsible for the destruction of lung tissue observed in pulmonary emphysema. In addition to emphysema, human leukocyte elastase is a suspected contributor to the pathogensis of disease states such as adult respiratory distress syndrome and rheumatoid arthritis.
Proteases are an important group of enzymes in the class of peptide-bond cleaving enzymes. These enzymes are essential for a variety of normal biological activities, including digestion, formation and dissolution of blood clots, the formation of active forms of hormones, the immune reaction to foreign cells and organisms, and in the body's response to various pathological conditions, such as pulmonary emphysema and rheumatoid arthritis.
Elastase, one of the proteases, is an enzyme able to hydrolyze elastin, a component of connective tissue. This property is not shared by the bulk of the proteases present in the body. Elastase acts on a protein's nonterminal bonds which are adjacent to an aliphatic amino acid. Of particular interest is neutrophil elastase, which exhibits a broad spectrum of activity against natural connective tissue substrates. In particular, the elastase of the granulocyte is important because granulocytes are participants in acute inflammation and in acute exacerbation of chronic forms of inflammation which characterize many major inflammatory diseases.
Proteases from granulocytes and macrophages are reported to be responsible for the chronic tissue destruction mechanisms associated with such inflammatory diseases as pulmonary emphysema, rheumatoid arthritis, bronchial inflammation, osteo arthritis, spondylitis, lupus, psoriasis, and acute respiratory distress syndrome. Proteases can be inactivated by inhibitors which bind tightly to enzymes to block their active sites. Naturally occuring protease inhibitors are part of the body's defense mechanism which are vital to the maintence of a state of well being. Without such a natural defense mechanism, the proteases would destroy any protein with which they came in contact. Naturally occuring enzyme inhibitors have been shown to have appropriate configurations which allow them to bind tightly to the enzymes. Thus, specific and selective inhibitors of the proteases are excellent candidates for potent anti-inflammatory agents useful in the treatment of the above conditions.
Proteases from granulocytes, leukocytes and macrophages are participants in a three-stage chain of events which occur during the progression of an inflammatory condition. During the first stage a rapid production of prostaglandins (PG) and related compounds synthesized from arachidonic acid occurs. The evidence suggests that protease inhibitors prevent PG production. During the second stage of progression of an inflammatory condition, a change in vascular permeability occurs, which causes a leakage of fluid into the inflammed site, which results in edema. The extent of edema is generally used as a means for measuring the progression of the inflammation. The process can be inhibited by various synthetic proteases inhibitors. The third stage of progression of an inflammatory condition is characterized by an appearance and/or presence of lymphoid cells, especially macrophages and polymorphonuclear leukocytes (PMN). It has been shown that a variety of proteases and released from the macrophages and PMN, thus indicating that the proteases play an important role in inflammation.
Rheumatoid arthritis is a degenerative inflammatory condition characterized by a progressive destruction of articular cartilage both on the free surface bordering the joint space and at the erosion front built up by synovial tissue toward the cartilage. This destructive process has been attributed to the protein-cutting enzyme elastase which is a neutral protease present in human granulocytes. This conclusion si supported by observations that there is an accumulation of granulocytes at the cartilage/pannus junction in rheumatoid arthritis and by recent investigation of the mechanical behavior of cartilage in response to attack by purified elastase which has shown the direct participation of granulocyte enzymes, especially elastase, in rheumatoid cartilage destruction.
The elastase inhibitory properties of several beta-lactam compounds is known in the art. U.S. Pat. No. 4,465,687 discloses N-acyl-derivatives of thienamycin esters and their use as anti-inflamatory agents.
U.S. Pat. No. 4,493,839 discloses derivatives of 1-carbapenem-3-carboxylic esters and their use as anti-inflammatory agents.
U.S. Pat. No. 4,495,197 discloses derivatives of N-carboxyl-thienamycin esters and analogs thereof and their use as anti-inflammatory agents.
U.S. Pat. No. 4,547,371 discloses substituted cephalosporin sulfones and their use as anti-inflammatory and anti-degenerative agents.
European Patent 124,081 discloses 3-substituted-3-cephem-4-carboxylate 1,1-dioxides and their use as anti-inflammatory and anti-degenerative agents.